Jim Brown, the man asked a question which, so far, you have not made a
reasonable attempt to answer. The original subject was "RFI cured with 1/4 wave
wire", less a request for 'help' than a request for ideas on why this approach
worked.
I did supply a reasonable hypothesis, and you disagreed, with little to no more
than opinion and hand wave. I am of the mind that perhaps you may not be as
studied or practiced with 'stubs' as some of us are, no matter the environment.
Please direct your attention to the question posed by the original poster. No
other plausible explanations have been presented that explain the first
poster's experience that I have seen, but, I may have missed something as I
have not received all replies on this subject.
73, Jim WB5WPA
On Sun,2/21/2016 10:06 AM, JW via RFI wrote:
> Has anyone said it yet - laying a 1/4 wavelength of wire out 'on the ground'
> creates an (albeit somewhat lossy) open-endedquarter wave 'stub' of somewhat
> indeterminate Z.
WAY too lossy to be useful.
> Recall, a quarter length away from the *open* end of a QW stubthe Z exhibits
> a low Z value. This is tantamount to 'walking' halfway around the perimeter
> of the Smith Chart (Z transformationor inversion in this case) and is the
> simple application of "The Quarter Wave Rule" that any RF savvy engineer
> should 'take tohis or her grave.
Of course. But of what use is such a "stub" in this application? And,
BTW, the Vp of the transmission line formed by the stub and the earth as
a return is much less than 1. Resonance of radials is also shifted by
their proximity to earth. Vp in the range of 0.7 is typical.
> This is, BTW, a common trick (open-ended QW stub or microstrip 'line') used
> on uWave MMICs to decouple Vgg and Vdd DC supply lines at millimeter wave
> lengths.
Useful on PC boards, but I can't think of why it would be useful here.
73, Jim K9YC
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